Any easy short-term fix would be to throw an error back to the user if we
detect simultaneous acceptance of conflicting packages when the archive admin
accepts a batch of packages.
Note that this generally only happens when they use the "queue" script tool as
the archive admin will try and accept package "foo" before they list how many
were uploaded. The UI package does not work like this, it requires you to
search for packages before you click on the packages so it would also be more
obvious that there are multiple uploads.
The queue script needs to die, in fire.